(a) Field of the Invention
The present invention relates to a synchronization error tracking device and method.
(b) Description of the Related Art
Since the direct sequence ultra wideband (DS-UWB) system transmits signals by using an ultra-wideband frequency, the signals generate great synchronization errors because of multipath fading caused by multipaths of a transmission channel in the case of transmitting signals, timing offsets generated between system clock signals used by the baseband of a transmitter/receiver, and frequency offsets generated by a mismatch of a local oscillator used for a radio frequency (RF) transceiver. Since performance of a UWB system receiver is deteriorated by inter-symbol interference (ISI) when the timing offsets and the frequency offsets are generated, it is required to continuously track and compensate the synchronization error in the payload transmission interval as well as the preamble transmission interval. Many methods for compensating the synchronization error have been known, but they are inefficient for the DS-UWB system for performing packet data communication by using the ultra-wideband frequency bandwidth. Also, the existing code division multiple access (CDMA) system is complicated because it uses individual modules so as to compensate the frequency offsets and control packet synchronization and symbol synchronization. For example, the industry standard 95 (IS-95) or the wideband CMDA (WCDMA) system uses a method for transmitting a pilot signal from a base station to a mobile station and acquiring initial code synchronization for the purpose of initial synchronization.
However, the UWB system must transmit a preamble sequence other than the pilot signal during communication on a piconet and acquire initial symbol synchronization and frame synchronization. Also, it has a problem of additionally compensating the synchronization error caused by the frequency offsets occurring between the clock signals used by the transmitter/receiver. Further, an initial synchronization acquisition method for using a searcher block to simultaneously acquire initial symbol synchronization and frame synchronization and additionally compensate the synchronization error caused by the frequency offset has been proposed. However, the conventional initial synchronization acquisition method is efficiently applicable to the DS-UWB system designed in the parallel processing structure, but it is only applicable to the preamble transmission interval transmitted to a preamble pattern and hence it is inapplicable to the data transmission interval.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.